Normal: These are your standard fare for a first person shooter, in which Bond collects weapons, shoots baddies and stares at the implausibly proportioned women like the old lech that he is.
Driving: When I first encountered the car driving missions, I thought they were a recipe for disaster - whole games are dedicated to driving a car, how could this be added in as such a small side note? In fact, it works superbly, because the handling on the cars is so slick that you feel totally in control and it is rarely frustrating. This style adds some much-needed variety.
Rail: On these missions, you have no control over the direction of the vehicle you are loaded into, but merely man the guns. These missions are a welcome distraction, but are less compelling than other activities on offer.

The variety of weapons is excellent, but you never get the feeling of duplicity and hence redundancy. There are some fantastic spray and pray moments to be had, and also a place for precision head-popping and the occasional sniping opportunity. It's pleasing to see that sniper rifles were not over-used, in a genre where reliance on distance combat is becoming rather stale.

As to be expected from a Bond game, copious gadgets are provided by Q, although not all of them entirely original. However, there are some very neat devices on offer, especially the Q-Claw that grabs onto certain plates and literally pulls you up. It's nice to see an FPS embrace its 3D opportunities so enthusiastically.

Bonuses

The bonus system is all rather complicated, but to outline:
Doing certain spectacular moves or kills gets you Bond Moves. These, along with various other skills like accuracy and speed, give you points.
Points get you awards for each level: Gold, Silver and Bronze.
Gold awards get you rewards for later in the game, for example the Golden Gun, or Unlimited Missiles.
Once you earn the Gold award, you can collect 007 Tokens hidden around the level and thus get a Platinum Award.
Platinum Awards get you bonuses in multiplayer, namely extra levels.
Complicated? You bet. But it provides a real incentive to replay the levels, and also to play like a real James Bond would - showing off just because you can; dispensing with the baddies in a dynamic and original way.

As yet, I have not had the opportunity to play human-on-human, but the lack of multiplayer bots is disappointing. On the other hand, there are a large variety of multiplayer maps, weapons and gadgets to choose from, and I have heard good things from those who have tried it. Rather cleverly, it's possible to gain extra maps for multiplayer by excellence in single player.

Walk-Through

The current FAQ and walk-through of choice is to be found at http://db.gamefaqs.com/console/ps2/file/agent_under_fire_c.txt